1. Field
The present disclosure relates to a method and an apparatus for controlling an internal-combustion engine.
2. Description of the Related Art
Such a type of control apparatus of an internal-combustion engine has been developed, as described in, for example, Japanese Unexamined Patent Application Publication No. 2011-122544. In the internal-combustion engine, part of exhaust gas is recirculated into an intake passage in the form of EGR gas by an EGR system. In addition, blended fuel generated by mixing low octane number fuel and high octane number fuel is injected from a fuel injection valve, and the ratio of the high octane number fuel to the blended fuel can be changed. Furthermore, the control apparatus detects engine knocking. Upon detecting engine knocking, the control apparatus supplies EGR gas into a cylinder using the EGR system to stop the knocking first. If the engine knocking continues even after a predetermined period of time has elapsed since the start of the supply of the EGR gas, the control apparatus increases the octane number of the fuel injected from the fuel injection valve by changing the ratio of the high octane number fuel to the blended fuel.